SEOUL, April 24 (Yonhap) -- President Moon Jae-in expressed strong regret Tuesday over the parliament's failure to revise the law on national referendums that has been declared void, and thus failing to enable a vote on a constitutional revision in the upcoming local elections.

"As the law on national referendums did not get decided before the deadline, the efforts to hold a concurrent vote on a constitutional revision in the local elections have fallen apart," the president said in a Cabinet meeting held at his office Cheong Wa Dae.

The remarks came after the rival parties failed to reach an agreement on the revision to the law on national referendums, which was ruled unconstitutional in 2014 for limiting the suffrage of South Korean citizens and expatriates in overseas countries.

The revision needed to be passed on Monday to allow the proposed vote on a constitutional change in the June 13 local elections.

"The National Assembly prevented a vote itself without even once deliberating the constitutional revision bill the president proposed based on the people's wish," Moon said, according to Cheong Wa Dae pool reports.

President Moon Jae-in speaks during a Cabinet meeting at the presidential office Cheong Wa Dae in Seoul on April 24, 2018. (Yonhap)

The president signed and sent the government-proposed constitutional revision bill to the National Assembly on March 26.

Moon said he will decide what to do with the government proposal after his summit with North Korean leader Kim Jong-un on Friday, but reiterated the constitutional revision will not benefit him or his government but only the people.

He vowed to make necessary changes even before a constitutional revision to help realize the proposed improvements to the people's lives.

"I ask each government ministry to continue pushing for policies and systems that reflect the purpose of the constitutional revision. I believe that is the least we can do for the people who expected their lives to improve through a constitutional revision," he said.

The ruling Democratic Party strongly blamed the main opposition Liberty Korea Party for the failure to realize a June revision, accusing the rival party of boycotting the National Assembly with an ulterior intention to derail a constitutional amendment.

"A precious opportunity to revise the Constitution after 31 years appears to be evaporating due to all kinds of obstructions the opposition party has put up," Rep. Woo Won-shik, floor leader of the ruling party, said during a meeting of party lawmakers.

Woo accused the LKP of coming up with one excuse after another to boycott the parliament in an attempt to thwart efforts to amend the basic law. The LKP has been staying away from April's extraordinary parliamentary session since its opening.

Rep. Kim Tae-nyeon, the DP's chief policymaker, also accused the LKP of politicizing the issue.

"A constitutional revision cannot be an object of partisan bickering," he said. "The Democratic Party has done its best to realize a June revision. All responsibility for the failure to pass the referendum law ... rests with the LKP and other opposition parties."

Now, political attention is shifting to when the revision can be put to a plebiscite.

The LKP has called for a referendum to be held in September, about three months after the term of the parliamentary panel on the constitutional change ends.

But the ruling party opposes the idea of holding a vote separately from the local elections, claiming it would cost some 120 billion won (US$111.4 million), and that such a referendum is unlikely to secure a high voter turnout.

Political observers raised the possibility of holding a referendum concurrently with the parliamentary elections in 2020.

The logistical issue aside, many challenges lie ahead for the revision.

Rival parties have remained poles apart over how to address the current concentration of powers in a single leader, which has been blamed for corruption, abuse of power and political polarization.

The ruling party seeks to change the current single five-year presidential term to a maximum of two consecutive four-year terms, and strengthen the rights of the prime minister and National Assembly.

But the LKP argues the ruling party's proposal would further strengthen presidential powers. It has advocated a power-sharing model under which the president takes control of national security, diplomacy and other external affairs, while the prime minster, to be picked by parliament, controls domestic affairs.